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Windows 7 Way Smarter With Graphics RAM

By - Source: Tom's Hardware US | B 59 comments

New Windows 7 WDDM 1.1 drivers save you RAM

In an earlier article, we described an advancement that the Windows 7 team made with desktop graphics by allowing more than one application to access the GDI (graphics device interface) stack at a time.

Allowing for more parallelism in the GDI will noticeably make things more responsive, but that wasn’t the only evolution that the software team made for the new OS. Windows 7 will now be more efficient in its use of RAM, which will have the positive effect of making everything run smoother – particularly on systems with shared graphics memory.

In Windows Vista, the more application windows you had open, the more memory required. Every window accounts for two memory allocations – one in video memory and one in system memory – which hold identical content.

The way Windows Vista does itThe way Windows Vista does itThe DWM (desktop window manager) is responsible for drawing the desktop with the GPU, which obviously requires the application window data in video memory. The same application window data is duplicated again in system RAM for the CPU to render independent of graphics hardware. This was inefficient obviously because of data redundancy.

The way Windows 7 does itThe way Windows 7 does itWindows 7 changes this by getting rid of the system memory copy entirely, which effectively cuts the memory consumed in half. Unlike the changes to the GDI stack detailed earlier, this new memory-saving behavior requires new drivers.

“We achieved the reduction in system memory by accelerating the common GDI operations through the graphics hardware - the WDDM drivers accelerate these to minimize the performance impact of the CPU read-back of video memory,” explained Ameet Chitre, a program manager on Microsoft’s Desktop Graphics feature team. “Since you save a lot of system memory, the paging activity gets reduced – as a result, your system responsiveness improves for the same workload.”

The new drivers that support the memory-saving change are designated WDDM 1.1. Older Windows Vista WDDM 1.0 drivers will still work fine with Windows 7, but do not take advantage of the new feature.

Desktop Window manager memory consumption comparison using WDDM 1.1 v. WDDM 1.0Desktop Window manager memory consumption comparison using WDDM 1.1 v. WDDM 1.0This change positively impacts real-world usability, but benchmarks may show a degradation in performance since the CPU has to fetch data from video RAM.

“The elimination of the duplicate system memory copies which ‘speed up’ certain operations introduced slightly reduced performance as the CPU now has to read data back from the video memory. An analysis of real-world application statistics showed that these operations were rare,” Chitre said. “Our observation has been that these slow-downs do not impact the end-user functionality directly and that the memory savings directly result in Windows 7 being much responsive overall.  The improvements overall are definitely noticeable on memory constrained PCs with shared memory graphics.”

The close-to-completion Windows 7 is nearly upon us. We learned on Saturday that the Release Candidate will be hitting MSDN and TechNet subscribers on April 30 with the public getting their Windows 7 RC download links on May 5.

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  • 24 Hide
    brother shrike , April 28, 2009 12:33 AM
    Shadow703793Good to see Microsoft doing things to optimize code. Now, could we please have a multi threaded OS?


    ummm.... Windows is multithreaded. has been for a while.
  • 16 Hide
    the_one111 , April 28, 2009 12:38 AM
    *begins to salivate over a new piece of technology*

    I feel..... nerdy...
  • 15 Hide
    LATTEH , April 27, 2009 11:41 PM
    man win 7 keeps getting better and better!
Other Comments
  • -9 Hide
    Shadow703793 , April 27, 2009 11:31 PM
    Good to see Microsoft doing things to optimize code. Now, could we please have a multi threaded OS?
  • 1 Hide
    thundercleese , April 27, 2009 11:38 PM
    I have a Radeon HD 3870 X2 with 1GB or video RAM and 8GB of system memory. I clearly don't use shared video memory and my GPU is never starved of memory either. Would it be wiser to stick with WDDM1.0 scheme in that case? And then use WDDM1.1 for my HTPC with an intergrated Radeon HD3200?

    ...Or would I even notice a difference on either system using either 1.0 or 1.1?
  • 15 Hide
    LATTEH , April 27, 2009 11:41 PM
    man win 7 keeps getting better and better!
  • 4 Hide
    tipoo , April 27, 2009 11:55 PM
    Sounds good to me.
  • 7 Hide
    7amood , April 28, 2009 12:00 AM
    yeah, it's clear that they are DOING...
    everyday, it becomes more interesting for me
    more efficiency... more development... more...
  • 3 Hide
    jsloan , April 28, 2009 12:06 AM
    wow this is amazing news, i cant wait for the rc.
  • 12 Hide
    jsloan , April 28, 2009 12:10 AM
    thundercleeseI have a Radeon HD 3870 X2 with 1GB or video RAM and 8GB of system memory. I clearly don't use shared video memory and my GPU is never starved of memory either. Would it be wiser to stick with WDDM1.0 scheme in that case? And then use WDDM1.1 for my HTPC with an intergrated Radeon HD3200?...Or would I even notice a difference on either system using either 1.0 or 1.1?


    you want to use 1.1 and take full advantage of windows 7 change. this is amazing, right now your graphics card memory is not directly used, instead windows writes to your ram memory and they are synced. this takes time, what microsoft is doing is directly writing to your video cards memory, saving the overhead of keeping the two synced. this is amazing and everyone should try to move over, baring problems...
  • 5 Hide
    Anonymous , April 28, 2009 12:28 AM
    See, this is how they avoid "perception problems" like in Vista, have the news constantly flood you with puff pieces on what a great OS this is, and thus, rumors that it doesn't suck spread like wildfire. This is why it's a new OS rather than Vista SP2.5, even though it's based on Vista. I hope it lives up to the hype, but don't let them "market" it to you like Apple does.
  • 24 Hide
    brother shrike , April 28, 2009 12:33 AM
    Shadow703793Good to see Microsoft doing things to optimize code. Now, could we please have a multi threaded OS?


    ummm.... Windows is multithreaded. has been for a while.
  • 11 Hide
    thundercleese , April 28, 2009 12:33 AM
    SkepticalSkepticSee, this is how they avoid "perception problems" like in Vista, have the news constantly flood you with puff pieces on what a great OS this is, and thus, rumors that it doesn't suck spread like wildfire. This is why it's a new OS rather than Vista SP2.5, even though it's based on Vista. I hope it lives up to the hype, but don't let them "market" it to you like Apple does.



    They're not "rumors". I have been using the Betas for a while now on many different plataforms and I can tell u Windows 7 is excellent.
  • 16 Hide
    the_one111 , April 28, 2009 12:38 AM
    *begins to salivate over a new piece of technology*

    I feel..... nerdy...
  • 2 Hide
    dafin0 , April 28, 2009 12:47 AM
    SkepticalSkeptic

    no need to market it to most people as they are using the beta/RC and can see that its a very solid product
  • 5 Hide
    mindless728 , April 28, 2009 12:50 AM
    nice, i actually want to switch to win7(i'll get it for free since i'm a computer science major at my college)
  • 2 Hide
    stryk55 , April 28, 2009 12:59 AM
    This advancement alone will definitely help Windows 7 appeal especially to those buying a low priced model from a PC manufacturer such as eMachines or Compaq. The biggest complaint with shared memory was slowdowns caused by this exact scenario.
  • 8 Hide
    MJRSnyder , April 28, 2009 1:28 AM
    The_One111I feel..... nerdy...


    don't we all
  • 8 Hide
    randomizer , April 28, 2009 1:34 AM
    Brother Shrikeummm.... Windows is multithreaded. has been for a while.

    Windows is as "multi-threaded" as games.
  • 2 Hide
    doomsdaydave11 , April 28, 2009 1:53 AM
    The_One111*begins to salivate over a new piece of technology*I feel..... nerdy...

    There's probably a reason for that :p 

    I agree with other posts. Windows 7 IS looking awesome.... I just wished it looked EXACTLY like Windows XP. I've used it for 8 years, and don't really ever wanna switch lol. DX10/11 and 64-bit on Windows 7 Ultimate would be the best thing ever :) .
  • 0 Hide
    Pei-chen , April 28, 2009 2:08 AM
    I have 8GB of system ram and 1GB video ram on my 4850. I see no reason why this wouldn’t be enough for Win7.
  • 3 Hide
    Pei-chen , April 28, 2009 2:12 AM
    randomizerWindows is as "multi-threaded" as games.

    Play 1080p file with XP and Vista x64 and you'll see the difference.
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